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We propose a 10-GHz 2 2 phased-array radio frequency (RF) receiver with an 8-bit linear phase and 15-dB gain control range using 65-nm complementary metal-oxide-semiconductor technology. An 8 X 8 phased-array receiver module is implemented using 16 2 X 2 RF phased-array integrated circuits. The receiver chip has four single-to-differential low-noise amplifier and gaincontrolled phase-shifter (GCPS) channels, four channel combiners, and a 50-Ω driver. Using a novel complementary bias technique in a phase-shifting core circuit and an equivalent resistance-controlled resistor-inductor-capacitor load, the GCPS based on vector-sum structure increases the phase resolution with weighting-factor controllability, enabling the vector-sum phase-shifting circuit to require a low current and small area due to its small 1.2-V supply. The 2 X 2 phased-array RF receiver chip has a power gain of 21 dB per channel and a 5.7-dB maximum single-channel noise-figure gain. The chip shows 8-bit phase states with a 2.39 degree root mean-square (RMS) phase error and a 0.4-dB RMS gain error with a 15-dB gain control range for a 2.5 degree RMS phaseerror over the 10 to 10.5-GHz band.

We propose a 10‐GHz 2 × 2 phased‐array radio frequency (RF) receiver with an 8‐bit linear phase and 15‐dB gain control range using 65‐nm complementary metal–oxide–semiconductor technology. An 8 × 8 phased‐array receiver module is implemented using 16 2 × 2 RF phased‐array integrated circuits. The receiver chip has four single‐to‐differential low‐noise amplifier and gain‐controlled phase‐shifter (GCPS) channels, four channel combiners, and a 50‐Ω driver. Using a novel complementary bias technique in a phase‐shifting core circuit and an equivalent resistance‐controlled resistor–inductor–capacitor load, the GCPS based on vector–sum structure increases the phase resolution with weighting‐factor controllability, enabling the vector–sum phase‐shifting circuit to require a low current and small area due to its small 1.2‐V supply. The 2 × 2 phased‐array RF receiver chip has a power gain of 21 dB per channel and a 5.7‐dB maximum single‐channel noise‐figure gain. The chip shows 8‐bit phase states with a 2.39° root mean‐square (RMS) phase error and a 0.4‐dB RMS gain error with a 15‐dB gain control range for a 2.5° RMS phase error over the 10 to10.5‐GHz band. [ABSTRACT FROM AUTHOR]

This paper presents a Ka-band beam steering transmitter exploiting a coupled varactor loaded transmission line (VLTL) phase shifter and a CMOS transmitter chip with an integrated frequency multiplier. The short-coupled line couplers placed along a single VLTL provides multi-phase outputs while minimizing the impedance mismatch and unequal power distribution along the VLTLs. The inherent phase-accumulating nature along the VLTL reduces the burden of wide phase control range required for using separate phase shifters for each channel. Additionally, the frequency multiplier with a multiplication ratio of 8 reduces the required amount of phase change at the reference frequency and therefore the tuning range of the varactor, which also minimize a change of line characteristic impedance to ensure the impedance matching of the VLTL. Hence, a 32 GHz phased array transmitter is implemented using a single VLTL phase shifter operating at a low reference frequency of about 4 GHz. The fabricated $1\times 4$ phased array transmitter achieves a continuous beam steering range of ±20° in the E-plane using a single control voltage. The sidelobe level is below -10 dB at all scan angles and the peak effective isotropic radiated power (EIRP) is 38.1 dBm at 31.6 GHz and the 3-dB bandwidth of 2.4 GHz is achieved.

Based on the traditional active noise control method, a phased-array secondary sound source was designed to replace the traditional sound source. Adopting a 4 × 4 array distributed design, we still maintain a single-in single-out system. Simulations show that the phased-array secondary sound source better controls noise reduction in a certain area of space, with better noise reduction effect, larger static area, and less impact on other non-control areas. A verification experiment was performed in a semi-anechoic chamber, with noise reduction conducted in different directions. The noise reduction effect of the phased-array secondary sound source was >10 dB higher than that of the traditional secondary sound source, with less influence on other points. The phased-array secondary sound source can be combined with tracking equipment to achieve a better follow-up noise reduction effect in space. [ABSTRACT FROM AUTHOR]

This paper focuses on the design aspects of the key components for a scalable phased-array system over the 200 GHz frequency range. A high-gain phase shifter chain for 220 to 240 GHz frequency range and a high-gain power amplifier (PA) with a high output power are designed in a 0.13- $\mu \text{m}$ SiGe BiCMOS technology. The phase shifter chain includes a low-noise amplifier (LNA), a vector modulator phase shifter (PS), and a gain-enhancing amplifier. The LNA is a five-stage cascode design. The vector modulator core is realized by two variable gain amplifiers based on the Gilbert cell architecture. A four-stage cascode design is used for the gain-enhancing amplifier. The phase shifter chain shows a measured gain of 18 dB at 230 GHz with a $360 {\mathrm { ^{\circ}}}$ phase tuning range and more than 10 dB of gain control. The chip achieves a minimum measured noise figure of 11.5 dB at 230 GHz and shows a wideband noise characteristic. The complete phase shifter chain chip consumes a dc power of 153 mW and occupies a 1.41 mm2 area. A high-power PA that is critical for a large phased-array system is designed. This paper presents a unique 4-way power combining technique utilizing a differential quadrature coupler. The realized balanced PA occupies an area of 0.67 mm2 and shows a measured peak gain of 21 dB at 244 GHz. The PA consumes 819 mW of dc power and delivers a maximum saturated output power $(P_{sat})$ of 7.1 dBm at 244 GHz and more than 4.3 dBm of $P_{sat}$ from 230 to 255 GHz.

PurposeTo compare the performance of an 8-channel surface coil/clamshell transmitter and 32-channel head array coil/birdcage transmitter for hyperpolarized 13 C brain metabolic imaging.MethodsTo determine the field homogeneity of the radiofrequency transmitters, B1 + mapping was performed on an ethylene glycol head phantom and evaluated by means of the double angle method. Using a 3D echo-planar imaging sequence, coil sensitivity and noise-only phantom data were acquired with the 8- and 32-channel receiver arrays, and compared against data from the birdcage in transceiver mode. Multislice frequency-specific 13 C dynamic echo-planar imaging was performed on a patient with a brain tumor for each hardware configuration following injection of hyperpolarized [1-13 C]pyruvate. Signal-to-noise ratio (SNR) was evaluated from pre-whitened phantom and temporally summed patient data after coil combination based on optimal weights.ResultsThe birdcage transmitter produced more uniform B1 + compared with the clamshell: 0.07 versus 0.12 (fractional error). Phantom experiments conducted with matched lateral housing separation demonstrated 8- versus 32-channel mean transceiver-normalized SNR performance: 0.91 versus 0.97 at the head center; 6.67 versus 2.08 on the sides; 0.66 versus 2.73 at the anterior; and 0.67 versus 3.17 on the posterior aspect. While the 8-channel receiver array showed SNR benefits along lateral aspects, the 32-channel array exhibited greater coverage and a more uniform coil-combined profile. Temporally summed, parameter-normalized patient data showed SNRmean,slice ratios (8-channel/32-channel) ranging 0.5-2.00 from apical to central brain. White matter lactate-to-pyruvate ratios were conserved across hardware: 0.45 ± 0.12 (8-channel) versus 0.43 ± 0.14 (32-channel).ConclusionThe 8- and 32-channel hardware configurations each have advantages in particular brain anatomy.

This brief presents a broadband SiGe power amplifier that achieves 30.1 dBm peak $\text{P}_{SAT}$ , 38.6% peak power-added efficiency (PAE), 90.9% large-signal fractional bandwidth (FBW) and a 3 dB bandwidth from 5.4 to 13.8 GHz. A balanced topology with two-stage, four-way combing is utilized to achieve watt-level output power and high-power efficiency in a wide range of operating frequency. Power stage is optimized and simulated from the perspective of high output power. At the output stage, a 90° coupler and two transformers are co-optimized for broadband output power combining as well as power matching. This balanced PA is implemented in a 0.13- $\boldsymbol {\mu }\text{m}$ SiGe BiCMOS process with a chip area (with pads) of 2.31 mm2. [ABSTRACT FROM AUTHOR]

A 28 GHz dual-mode phase-invariant wide-dynamic-range variable-gain amplifier (VGA) with adaptive phase compensators is presented for use as a gain control element in a beamforming IC, which must have a small chip size and low power consumption. It consists of a single-stage differential amplifier with main and auxiliary signal paths, where the auxiliary paths are introduced to achieve most-significant-bit (MSB) gain control. The wide-gain dynamic range is also covered through a least-significant-bit (LSB) gain-control scheme, which is implemented with bias control of common gate (CG) transistors in the main signal paths. In addition, the phase variations due to the gain controls are drastically reduced by introducing phase compensators for both gain controls. The proposed VGA shows a gain dynamic range of 24 dB, maximum gain of 13 dB and root-mean-square (RMS) phase error of 2.77 degrees at 28 GHz. The maximum DC power consumption is 24 mW at the maximum gain, the minimum is 4 mW at the minimum gain, and the chip size is 0.066 mm2. [ABSTRACT FROM AUTHOR]

This article presents a temperature compensated transmitter for phased-array applications. The high-temperature effects on each individual transmitter building block are studied and compensated to mitigate the performance variations. Furthermore, a new active, tunable, and variable gain phase shifter VGPS) architecture is proposed, which features low-performance variation with temperature and high gain without compromising the phase shift range. A temperature sensor is designed to adaptively adjust the critical dc bias voltages to minimize the variation of the active devices. A class- $\text{F}^{-1}$ power amplifier PA) is designed, as the last stage in the transmitter chain, and its performance variation is compensated through the VGPS stage by adaptively tuning its characteristics. Gallium-nitride (GaN)-on-silicon-carbide (SiC) high-electron-mobility transistors (HEMTs) are adopted as the active devices and a voltage-controlled capacitor (varactor) used in the VGPS stage. The transmitter is prototyped on a piece of Rogers 4003C substrate, and the system performance is measured. The transmitter has the minimum and the maximum small-signal gain of 5.2 and 31.5 dB, respectively, with the maximum variation of < 2.3 dB across the temperature range and the frequency range of 2–2.1 GHz. The insertion phase variation also remains below 6.5° across the phase shift, temperature, and frequency range. The maximum output power and power added efficiency (PAE) are measured to be 33 dBm and 58%, respectively, at the maximum ambient temperature of 220 °C. The measurement results also show that the transmitter is able to transmit 64-QAM signals with the data rate of 120 Mb/s at the maximum ambient temperature of 220 °C. [ABSTRACT FROM AUTHOR]

Purpose – In this work, a microstrip antenna array for wireless power transfer (WPT) application is reported. The proposed 4 × 4 antenna array operating at 16 GHz is designed using a flexible Kapton polyimide substrate for a far-field charging unit (FFCU). Design/methodology/approach – The proposed antenna is designed using the transmission line model on a flexible Kapton polyimide substrate. The finite element method (FEM) is used to perform the full-wave electromagnetic analysis of the proposed design. Findings – The antenna offers −10 dB bandwidth of 240 MHz with beam width and broadside gain found to be 29.4° and 16.38 dB, respectively. Also, a very low cross-polarization level of −34.23 dB is achieved with a radiation efficiency of 36.67%. The array is capable of scanning −15° to +15° in both the elevation and azimuth planes. Originality/value – The radiation characteristics achieved suggest that the flexible substrate antenna is suitable for wireless charging purposes.

We demonstrate the effectiveness of total focusing methods (TFM) using Rayleigh waves for surface and sub-surface nondestructive inspection of different metals. The relatively low velocity of Rayleigh waves leads to sub-100 μm resolution imaging, with a penetration depth approximately equal to its wavelength. This allows for imaging and sizing sub-millimetric holes, possibly on coated material, as well as cracks, segregations, and other defects. The waves can propagate over long distances and works with curved surfaces or very close to edges. This shows potential for a new type of real-time surface inspection of large surfaces, with excellent spatial resolution. The process is free of chemical preparation and cleaning, and can be fully automated, from acquisition to decision or for making surface digital twin. [ABSTRACT FROM AUTHOR]

A 1.9-dB NF K-band phased-array receiver (RX) is presented, which employs the hybrid packaged 65-nm CMOS beamformer and 0.1- $\mu \text{m}$ GaAs LNAs based on the fan-out wafer-level chip-scale packaging (WLCSP) technology. Power-efficient gain and phase tuning blocks are utilized to reduce power consumption. Temperature-healing design methodology is adopted to ensure nearly constant gain response versus temperature variations. The proposed phased-array RX only consumes 30.2-mW dc power per channel and achieves < 1.2-dB gain variation and < 0.9-dB NF variation from −40 °C to 85 °C. [ABSTRACT FROM AUTHOR]

Purpose: High-intensity focused ultrasound (HIFU) is challenging in the liver due to the respiratory motion and risks of near-/far-field burns, particularly on the ribs. We implemented a novel design of a HIFU phased-array transducer, dedicated to transcostal hepatic thermo-ablation. Due to its large acoustic window and strong focusing, the transducer should perform safely for this application. Material and Methods: The new HIFU transducer is composed of 256 elements distributed on 5 concentric segments of a specific radius (either 100, 111, or 125 mm). It has been optimally shaped to fit the abdominal wall. The shape and size of the acoustic elements were optimized for the largest emitting surface and the lowest symmetry. Calibration tests have been conducted on tissue-mimicking gels under 3-T magnetic resonance (MR) guidance. In-vivo MR-guided HIFU treatment was conducted in two pigs, aiming to create thermal ablation deep in the liver without significant side effects. Imaging follow-up was performed at D0 and D7. Sacrifice and post-mortem macroscopic examination occurred at D7, with the ablated tissue being fixed for pathology. Results: The device showed −3-dB focusing capacities in a volume of 27 × 46 × 50 mm3 as compared with the numerical simulation volume of 18 × 48 × 60 mm3. The shape of the focal area was in millimeter-range agreement with the numerical simulations. No interference was detected between the HIFU sonication and the MR acquisition. In vivo , the temperature elevation in perivascular liver parenchyma reached 28°C above physiological temperature, within one breath-hold. The lesion was visible on Gd contrast-enhanced MRI sequences and post-mortem examination. The non-perfused volume was found in pig #1 and pig #2 of 8/11, 6/8, and 7/7 mm along the LR, AP, and HF directions, respectively. No rib burns or other near-field side effects were visually observed on post-mortem gross examination. High-resolution contrast-enhanced 3D MRI indicated a minor lesion on the sternum. Conclusion: The performance of this new HIFU transducer has been demonstrated in vitro and in vivo. The transducer meets the requirement to perform thermal lesions in deep tissues, without the need for rib-sparing means. [ABSTRACT FROM AUTHOR]

Prior studies have highlighted the importance of calibrating receiver antennas in target direction-of-arrival (DOA) estimation and surface current measurement for high-frequency (HF) radar systems. It is worth noting that the calibration contributes to the performance of both shore-based HF radar and platform-mounted HF radar. Compared with shore-based HF radar, the influence of six-degrees-of-freedom (six-DOF) platform motion should be considered in the calibration of platform-mounted HF radar. This paper initially describes a calibration scheme that receives phased-array antennas for an anchored platform-mounted HF radar incorporating a model of free rotation, which is called yaw rotation and dominates the six-DOF platform motion in this study. In the presence of yaw rotation, the amplitude and phase of the source calibration signal from the other shore-based radar sites reveal the directional sensitivity of the receiver phased-array antennas. The calibration of receiver phased-array antennas is composed of channel calibration (linking cables and receiver hardware calibration) and antenna pattern calibration. The antenna pattern at each bearing can be represented by the Fourier series. The estimation of channel calibration and antenna pattern calibration depends on an overdetermined HF radar system consisting of observed values and theoretical constraints, so the least-squares fits of the channel calibration coefficients and antenna pattern calibration coefficients are obtained. The experimental results show that the target DOA estimation and surface current measurement can be improved if the phased-array platform-mounted HF radar system is calibrated. [ABSTRACT FROM AUTHOR]

We present a broadband parallel-combined compact Doherty power amplifier (PA) in a 28-nm bulk complementary metal–oxide–semiconductor (CMOS) device technology for fifth-generation (5G) millimeter-wave (mm-Wave) frequency band (n257, n258, and n261) applications. The proposed Doherty PA has a single transformer (TF)-based output matching network and an equivalent quarter-wavelength line placed between the carrier and peaking amplifiers, absorbing transistors’ output parasitic capacitances. Therefore, the Doherty PA occupies a very small die area and has a wide bandwidth characteristic compared with the conventional Doherty PA output matching network topologies (e.g., parallel- and series-combined Doherty PA output matching networks). The two-stage differential Doherty PA is implemented, which shows a saturation output power ($P_{\mathrm {OUT}}$) of >18.8 dBm and a peak power-added efficiency (PAE) of >30% at 27 GHz. It also exhibits a linear $P_{\mathrm {OUT}}$ of 12.4 dBm and an average PAE of 20.2% for 100 MHz 5G NR signal ($P_{\mathrm {OUT}}$ of 11.4 dBm and PAE of 18.1% for 8 $\times $ 100 MHz carriers) at the EVM of −25 dB. Over the frequency range of 24.5–29.5 GHz, the PA achieves a linear $P_{\mathrm {OUT}}$ of >11.2 dBm and a PAE of >14.5% (drain efficiency >20.8%). This PA occupies 640 $\mu \text{m}\,\,\times $ 250 $\mu \text{m}$ (core only) and is successfully integrated into a 32-channel RF phased-array transceiver IC for the first time. The IC die area is 10.2 mm $\times $ 6.4 mm and consumes about 120 mW per channel at $P_{\mathrm {OUT}}$ of 10.0 dBm. [ABSTRACT FROM AUTHOR]

There have been scarce interactions between microwave circuits and display technologies over the past few decades. However, the two share many similarities leaving room for integration and co-development. Hence, we present a Circuit-on-Display (CoD) concept that dually functions as a radio-frequency transceiver and a high-resolution touch screen display. The approach is realized through a flexible, invisible hybrid electromagnetic sensor (HEMS) which is situated inside a high-resolution display panel. The CoD is integrated within a real-life millimeter-wave 5G NR Android-based cellular handset prototype to demonstrate a foreside beamforming coverage and a touch operation with high-resolution and optimal image quality. The devised HEMS prototype independently features flexibility, optically invisibility (transmittance >88%), and multi-functionality (system gain of 20.72 dB, beam scanning range of ±40°, and mutual capacitance change ratio >4.42%). The devised approach provides a new class of approach to enable microwave integrated circuits for new generation wireless electronics.

PurposeHigh-intensity focused ultrasound (HIFU) is challenging in the liver due to the respiratory motion and risks of near-/far-field burns, particularly on the ribs. We implemented a novel design of a HIFU phased-array transducer, dedicated to transcostal hepatic thermo-ablation. Due to its large acoustic window and strong focusing, the transducer should perform safely for this application.Material and MethodsThe new HIFU transducer is composed of 256 elements distributed on 5 concentric segments of a specific radius (either 100, 111, or 125 mm). It has been optimally shaped to fit the abdominal wall. The shape and size of the acoustic elements were optimized for the largest emitting surface and the lowest symmetry. Calibration tests have been conducted on tissue-mimicking gels under 3-T magnetic resonance (MR) guidance. In-vivo MR-guided HIFU treatment was conducted in two pigs, aiming to create thermal ablation deep in the liver without significant side effects. Imaging follow-up was performed at D0 and D7. Sacrifice and post-mortem macroscopic examination occurred at D7, with the ablated tissue being fixed for pathology.ResultsThe device showed −3-dB focusing capacities in a volume of 27 × 46 × 50 mm3 as compared with the numerical simulation volume of 18 × 48 × 60 mm3. The shape of the focal area was in millimeter-range agreement with the numerical simulations. No interference was detected between the HIFU sonication and the MR acquisition. In vivo, the temperature elevation in perivascular liver parenchyma reached 28°C above physiological temperature, within one breath-hold. The lesion was visible on Gd contrast-enhanced MRI sequences and post-mortem examination. The non-perfused volume was found in pig #1 and pig #2 of 8/11, 6/8, and 7/7 mm along the LR, AP, and HF directions, respectively. No rib burns or other near-field side effects were visually observed on post-mortem gross examination. High-resolution contrast-enhanced 3D MRI indicated a minor lesion on the sternum.ConclusionThe performance of this new HIFU transducer has been demonstrated in vitro and in vivo. The transducer meets the requirement to perform thermal lesions in deep tissues, without the need for rib-sparing means.

This article presents a 130 nm SiGe BiCMOS four‐channel satellite communication receiver. Phased‐array system has become the optimal solution for satellite communication due to the electrical steering nature. In order to obtain wider bandwidth, higher precision of phase shift and smaller chip size, an improved quadrature network and a phase compensation technique are proposed in this article. Each channel consists of a cascade low noise variable gain amplifier with a high Q value inductor and an active vector synthetic phase shifter. The measurement results show that the receiver consumes only 193 mA current under 1.6 V supply voltage. The chip can achieve a gain of more than 23 dB (including synthesizer losses) from 19 to 23 GHz. From 17.5 to 23 GHz, the RMS phase shifting accuracy and attenuation accuracy are less than 2.7° and 1.1 dB, respectively. The noise figure and the gain variation are less than 2.3 dB and ± 1.5 dB, respectively. The total chip area is 3.5 × 1.8 mm2. [ABSTRACT FROM AUTHOR]

A novel architecture of a digital modulated polar phased-array transmitter with phase modulation (PM) phase-shifting and feed-forward controlled dynamic matching (FFCDM) is presented in this article. Phase-shifting in a PM signal path is utilized in each element, which shares many components including a phase modulator, baseband, and IF components. The characteristics of the proposed architecture are analyzed. With a constant envelope of PM signals, the implicit nonlinearity of the phase shifter in this architecture has low impact on the linearity performance of a phased-array system. Meanwhile, low phase error can be achieved by high-resolution phase interpolation with the digital predistortion (DPD) technique. Efficiency for both saturated and 6-dB back-off power is enhanced by digital power amplifier (DPA) with FFCDM. As a proof of concept, a 3–7 GHz 4-element phased-array transmitter is designed and fabricated in 40-nm CMOS based on the proposed method. The measured root-mean-square (rms) phase error of 0.3°, effective phase shifting resolution of 9-bit, and peak system efficiency of 38.2% are achieved. For 40 MHz 64-QAM modulation signal, it exhibits EVM of 5.38% and 5.37%, $P_{\text {out}}$ of 14.30 and 14.46 dBm, and PAPR of 7.08 and 6.97 at 3.5 and 5.2 GHz, respectively. The measured peak EIRP is 35.6 dBm with a unit antenna gain of 2.98 dBi at 5 GHz. The radiation patterns with 0°, 15°, 30°, and 45° steering are measured based on monopole antennas. Meanwhile, the array achieves < 4.7% and < 5.9% EVM for 64-QAM signals with bandwidths of 20 and 40 MHz, respectively. [ABSTRACT FROM AUTHOR]

This letter presents a differential 5-bit switch-type phase shifter (PS) that is based on a 65-nm CMOS process. This PS uses a new differential PS unit, which includes a high-pass state and a low-pass state. The strengths of this PS unit include low-phase error and low-amplitude error between two states, which can effectively improve the performance of the entire 5-bit PS. The fabricated 5-bit PS has a low average insertion loss of <8.0 dB, low root mean square (rms) phase error of <5.9°, and low rms amplitude error of <0.22 dB in 35–41.9 GHz. It also has a compact size of 0.125 mm2. [ABSTRACT FROM AUTHOR]

In this brief, a frequency-reconfigurable phase shifter (PS) with a substrate-shield-based inductor for 5G applications is presented. This PS can switch its operating bands between 26.5–29.5 GHz and 37–40 GHz by a single control voltage. Because of the switch-type topology, this PS has the benefit of zero power consumption. To verify the utility of this circuit, a 5-bit frequency-reconfigurable PS was designed and fabricated with a 65-nm CMOS process, where 4 bits out of the 5-bit PS employ the proposed frequency-reconfigurable PS. The 5-bit PS has the root mean square (RMS) phase error of 3.7°–12.2° and the RMS amplitude error of 0.4–0.96 dB in 26.5–29.5 GHz. After the control voltage was changed, The PS also had an RMS phase error of 1.6°–8° and an RMS amplitude error of 0.43–0.64 dB in another band (37–40 GHz). According to the aforementioned results, the proposed frequency-reconfigurable PS can support the frequency bands of n257 and n260, which were released by 3rd Generation Partnership Project (3GPP). Hence, the proposed PS is an effective solution for 5G millimeter wave applications. [ABSTRACT FROM AUTHOR]

This brief presents a variable-gain low-noise amplifier (VG-LNA) with a common gate (CG) cross-summing configuration, which is fabricated using a 65-nm RF CMOS process. It has a wide gain control range as well as a high input 1 dB gain compression point (IP1dB) at high-gain by introducing a split common-gate transistor (SCGT) technique. In addition, output phase compensation is achieved by adopting a tuning capacitor at the cascode node. This LNA is designed as 2-stage cascode, and the area excluding the pad is 0.2 mm2. It consumes 25.2 mW with a 1.2-V power supply. It shows a gain of 25 dB and a noise figure of 3.4 dB at 22 GHz. The measured minimum IP1dB is −27.5 dBm, and the root-mean-square phase error is 0.34° over the gain control range of 14 dB at 22 GHz. [ABSTRACT FROM AUTHOR]

This paper provides a detailed overview of an optically invisible phased‐array antenna‐on‐display (AoD) technology for microwave, millimeter‐wave (mmWave), and sub‐THz wireless scenarios such as wireless communication, radar, sensing etc. The fundamental AoD configuration and stack‐up are introduced with numerical results, which proves the trade‐off relationship between optical transmittance and RF conductivity. A transverse magnetic patch antenna for Wi‐Fi and Bluetooth accessibility is implemented on the active display panel of a real‐life smartwatch device. The fully functional smartwatch prototype including the electromagnetic wrist phantom features a total radiation efficiency of 22% at 2.4 GHz. The optically invisible phased‐array AoD is fully integrated within the view area of high‐resolution OLED display panels of mmWave 5G NR cellular handsets. The fabricated cellular handset prototype including optically invisible beamforming AoD features optical transmittance of more than 88 % and beam scanning of ± 30° with the estimated maximum EIRP of 14.4 dBm. The over‐the‐air test confirms that the fabricated phased‐array AoD prototype satisfies the 3GPP's EVM performance requirement for 5G NR cellular devices. Future work collectively aims to serve as a catalyst for the emergence of future sub‐THz 6G mobile devices. [ABSTRACT FROM AUTHOR]

Prior studies have highlighted the importance of calibrating receiver antennas in target direction-of-arrival (DOA) estimation and surface current measurement for high-frequency (HF) radar systems. It is worth noting that the calibration contributes to the performance of both shore-based HF radar and platform-mounted HF radar. Compared with shore-based HF radar, the influence of six-degrees-of-freedom (six-DOF) platform motion should be considered in the calibration of platform-mounted HF radar. This paper initially describes a calibration scheme that receives phasedarray antennas for an anchored platform-mounted HF radar incorporating a model of free rotation, which is called yaw rotation and dominates the six-DOF platform motion in this study. In the presence of yaw rotation, the amplitude and phase of the source calibration signal from the other shore-based radar sites reveal the directional sensitivity of the receiver phased-array antennas. The calibration of receiver phased-array antennas is composed of channel calibration (linking cables and receiver hardware calibration) and antenna pattern calibration. The antenna pattern at each bearing can be represented by the Fourier series. The estimation of channel calibration and antenna pattern calibration depends on an overdetermined HF radar system consisting of observed values and theoretical constraints, so the least-squares fits of the channel calibration coefficients and antenna pattern calibration coefficients are obtained. The experimental results show that the target DOA estimation and surface current measurement can be improved if the phased-array platform-mounted HF radar system is calibrated.

We present an air-coupled ultrasonic imaging system based on a 40-kHz $8\times 8$ phased-array for 3-D real-time localization of multiple objects in the far-field. By attaching a waveguide to the array, the effective interelement spacing is reduced to half wavelength. This enables grating lobe-free transmit and receive beamforming with a uniform rectangular array of efficient low-cost transducers. The system further includes custom transceiver electronics, an field programmable gate array (FPGA) system-on-chip and a PC for GPU accelerated frequency domain signal processing, consisting of matched filtering, conventional beamforming, and envelope extraction using Nvidia Compute Unified Device Architecture (CUDA) and OpenGL for visualization. The uniform rectangular layout allows utilizing multiple transmit and receive methods, known from medical imaging applications. Thus, the system is dynamically adaptable to maximize the frame rate or detection range. One implemented method demonstrates the real-time capability by transmitting a hemispherical pulse (HP) with a single transducer to irradiate the surroundings simultaneously, whereas all transducers are used for echo reception. The imaging properties, such as axial and lateral resolution, field of view and range of view, are characterized in an anechoic chamber. The object localization is validated for a horizontal and vertical field of view of ±80° and a range of view of 0.5–3 m with 29 frames/s. Using the same system, a comparison between the HP method and the dynamic transmit beamforming method, which transmits multiple sequential beamformed pulses for long-range localization, is provided. [ABSTRACT FROM AUTHOR]

This paper presents the design and the implementation of a fully integrated active phase shifter for beamforming at 5.8 GHz. The proposed circuit, implemented in a 0.25 µm BiCMOS SiGe:C process, is based on an original architecture using an injection-locked oscillator (ILO) associated with an in-phase/quadrature (IQ) modulator. The dynamic behaviour of an ILO is first analysed theoretically and important characteristics are deduced. At 2.5 V power supply voltage and total power dissipation of only 92.5 mW, the proposed circuit allows to obtain a 360° phase shift range and occupies 1.43 mm2. This phase shift is synthesised using the ILO for fine-tuning and the IQ modulator for coarse tuning. [ABSTRACT FROM AUTHOR]

This article proposes a 28-GHz full-duplex (FD) phased arrays, which consists of 64-element transmitting and receiving arrays, and a 28-GHz radio frequency (RF) canceller. The phased arrays are designed with $2\times 2$ beamformer chips, and the transmitter (TX) and receiver (RX) arrays are oriented to have cross polarized configurations for high isolation. The 28-GHz RF canceller is based on an identical $2\times 2$ beamformer chip with two external different delay taps. Since the canceller is located at the input and output ports of arrays instead of antennas, it cannot eliminate the nonlinearities and noises in the phased arrays. Therefore, these nonlinearities and noise in the TX and RX arrays are experimentally analyzed to demonstrate that the proposed cross-polarized arrays have enough isolation to achieve suppression to the level of the RX noise floor. The FD phased-array system at 28.5–29.5 GHz has 57-dB isolation between the TX input and RX output ports, where the cross-polarization improves 10-dB isolation comparing to co-polarization and the RF canceller provide additional 10-dB self-interference (SI) suppression. Also, the nonlinearities and noise components of the received SI signals are lower than the noise floor at the output of the RX array. The system requires only 15.5-dB of additional digital cancellation to reduce the SI to the RX noise floor of 1-GHz bandwidth while maintaining the transmitting EIRP at 41 dBm. [ABSTRACT FROM AUTHOR]

This article presents a differential vector modulator-based phase rotator (PR) performing 360° full-span phase interpolation over a first-ever decade-wide instantaneous bandwidth from 2 to 24 GHz. The proposed PR employs a three-stage transformer poly-phase network with high-precision and ultra-wide-bandwidth, two highly linear 5-bit variable gain amplifiers (VGAs), a differential series–shunt–series inductor peaking load network for bandwidth extension and an open-drain buffer. It is implemented in a standard 65-nm bulk CMOS process with a chip area of 1.2 mm $\times1.8$ mm. The measurement results demonstrate the maximum rms quantization phase error of 1.22° within a 1.5-dB output magnitude variation for full 360° interpolations from 2 to 24 GHz and the −3-dB magnitude bandwidth is up to 19 GHz, respectively. Moreover, due to the wideband high-quality in-phase/quadrature ($I/Q$) signal generation and high-precision $I/Q$ interpolation of the VGAs, the PR can perform full-span phase synthesis with a constant set of phase shift code settings for all the operating frequencies. For interpolating 22.5°/15° phase step over the 360° full-span, the “one-code” setting operation achieves an rms phase error of 1.56°/1.42° from 3.5 to 22.5 GHz without any frequency-dependent code/look-up table (LUT), tunable element, or band-selection switch. Furthermore, with the “one-code” setting operation, the modulation tests demonstrate measured rms error-vector-magnitude (EVM) values below 5% for a 50-kSym/s QPSK signal from 3.3 to 22.3 GHz and for a 16-quadratic-amplitude modulation (QAM) signal from 2.7 to 22 GHz. [ABSTRACT FROM AUTHOR]

A pulsed chirping phased-array transceiver (TRX) is demonstrated for X-band synthetic aperture radar (SAR) application. The phased-array TRX is implemented on a single CMOS chip with beamsteering/beamforming capabilities. The chip-scale radar TRX is composed of four transmitters (TXs) and four receivers (RXs) operating at 10-GHz center frequency with 1-GHz bandwidth (BW). To achieve the wideband beamsteering with a fine angle step, the two-stage delay control in the TX is proposed, where a delay-locked loop (DLL) -based multi-phase synthesizer (MPS) is used to control the coarse true-time delay of the baseband chirp, and the active phase shifters (PS) in radio frequency (RF) path are used for fine phase tuning. Fabricated in a 65-nm CMOS technology, the TRX consumes 228 mW for each channel at a 1.2-V supply, delivering ~10.2-dBm power with <1.3-dB ripple. The delay-line test shows that the dechirped signal achieves −13-dB peak-to-sidelobe ratio (PSLR) and the phase coherence error is within ±1.2° at a chirp rate of 1 MHz/ $\mu \text{s}$. The prototype phased-array radar TRX chip is demonstrated with the antenna arrays consisting of Vivaldi antennas of 8-dBi gain, 6-GHz BW, and 6-cm pitch distance. Experiments indicate that beamsteering/beamforming up to ±60° with a step of ~1° is achieved. SAR imaging experiment is carried out based on both the two-stage beamsteering in the TXs and the digital beamforming in the RXs, proving the capability of the prototype phased-array radar TRX chip for the SAR imaging applications. [ABSTRACT FROM AUTHOR]

A 35-GHz transmitter (TX) and receiver (RX) front end in CMOS technology for Ka-band frequency-modulated continuous wave (FMCW) phased-array radar transceivers are presented in this article. While typical FMCW phased-array radar transceivers use RF-path phase-shifting scheme for both TX and RX front ends, the Ka-band TX and RX front ends presented in this article are designed for TX-analog and RX-digital beamforming phased-array radar system. The link budget for the Ka-band phased-array radar transceiver is investigated. In order to improve the TX output power level, a power amplifier (PA) with a four-way power splitter/combiner is introduced. The detailed analyses and design considerations of the PA are investigated. The proposed TX and RX front ends are implemented and fabricated in a 1P9M 65-nm CMOS technology. The measured TX output power is 19 dBm. To the best of authors’ knowledge, it is the highest output power FMCW module at the Ka-band using CMOS technology reported so far. The RX achieves a conversion gain of 29.6 dB. The TX occupies 1.42 mm2 and consumes 588 mW. The RX occupies 0.59 mm2 and consumes 72 mW. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique to synchronize a swarm of sensor nodes at the RF domain and produce coherent radiation from the sensor nodes to increase the amplitude of the reflected signal. A network is formed by an array of microchips that are wirelessly powered, and upon activation, radiate back an RF signal. The phase of the radiated signals from each microchip is synchronized using a wireless reference signal. This technique results in a coherent amplitude combing and power amplification. The microchips are fabricated in a 180-nm CMOS SOI technology. Each microchip occupies a total area of $3.9\times 0.7\,\,\textit {mm}^{2}$ that includes three on-chip dipole antennas that are used for power delivery, injection locking, and back RF reflection. Measurement results reveal that a reference signal in a frequency range of 7.72-7.79 GHz can successfully synchronize the reflected signals radiated from the microchips through a sub-harmonic injection locking scheme. A wireless reference signal of 7.733 GHz synchronizes an array of $2\times2$ microchips. The microchips are locked to half of the reference frequency and produce coherent radiation at 3.866 GHz. This scheme results in a power elevation of ~12 dB on the reader side. [ABSTRACT FROM AUTHOR]

This article presents a low-cost and area-efficient 28-GHz CMOS phased-array beamformer chip for 5G millimeter-wave dual-polarized multiple-in-multiple-out (MIMO) (DP-MIMO) systems. A neutralized bi-directional technique is introduced in this work to reduce the chip area significantly. With the proposed technique, completely the same circuit chain is shared between the transmitter and receiver. To further minimize the area, an active bi-directional vector-summing phase shifter is also introduced. Area-efficient and high-resolution active phase shifting could be realized in both TX and RX modes. In measurement, the achieved saturated output power for the TX-mode beamformer is 15.1 dBm. The RX-mode noise figure is 4.2 dB at 28 GHz. To evaluate the over-the-air performance, 16 H+16 V sub-array modules are implemented in this work. Each of the sub-array modules consists of four 4 H+4 V chips. Two sub-array modules in this work are capable of scanning the beam from −50° to +50°. A saturated EIRP of 45.6 dBm is realized by 32 TX-mode beamformers. Within 1-m distance, a maximum SC-mode data rate of 15 Gb/s and the 5G new radio downlink packets transmission in 256-QAM could be supported by the module. A 2 × 2 DP-MIMO communication is also demonstrated with two 5G new radio 64-QAM uplink streams. Thanks to the proposed area-efficient bi-directional technique, the required core area for a single element-beamformer is only 0.58 mm2. Compact and low-cost 5G millimeter-wave MIMO systems could be realized. [ABSTRACT FROM AUTHOR]

This article presents the first 39-GHz phased-array transceiver (TRX) chipset for fifth-generation new radio (5G NR). The proposed transceiver chipset consists of 4 sub-array TRX elements with local-oscillator (LO) phase-shifting architecture and built-in calibration on phase and amplitude. The calibration scheme is proposed to alleviate phase and amplitude mismatch between each sub-array TRX element, especially for a large-array transceiver system in the base station (BS). Based on LO phase-shifting architecture, the transceiver has a 0.04-dB maximum gain variation over the 360° full tuning range, allowing constant-gain characteristic during phase calibration. A phase-to-digital converter (PDC) and a high-resolution phase-detection mechanism are proposed for highly accurate phase calibration. The built-in calibration has a measured accuracy of 0.08° rms phase error and 0.01-dB rms amplitude error. Moreover, a pseudo-single-balanced mixer is proposed for LO-feedthrough (LOFT) cancellation and sub-array TRX LO-to-LO isolation. The transceiver is fabricated in standard 65-nm CMOS technology with flip-chip packaging. The 8TX–8RX phased-array transceiver module 1-m OTA measurement supports 5G NR 400-MHz 256-QAM OFDMA modulation with −30.0-dB EVM. The 64-element transceiver has a EIRPMAX of 53 dBm. The four-element chip consumes a power of 1.5 W in the TX mode and 0.5 W in the RX mode. [ABSTRACT FROM AUTHOR]

Fatigue of welded tubular K‐joints made of circular hollow sections – standard‐compliant design and weld quality In steel and composite bridges, in industry structures, cranes or in the offshore industry trusses of circular hollow sections (CHS) with welded tubular K‐joints and thick‐walled chords are subject to high fatigue loading. However, normative regulations have been lacking so far for a fatigue verification of these joints. This paper summarises the results of the FOSTA research project P1163 dealing with this topic. Two important aspects of the investigations were the extension of the application range to large‐sized CHS (d > 500 mm) and the development of practice‐oriented recommendations for fabrication and quality assurance of weld geometries. For this purpose, fatigue tests were conducted on large‐sized CHS‐joints (chord dimensions 660 mm × 60 mm) and on K‐joints with specified weld root opening size and weld shape. These studies were accompanied by systematic ultrasonic tests with phased‐array which also were used for the development of an inspection method for these complex weld geometries. Based on the results, a proposal for a DASt‐Guideline was finally elaborated to promote the acceptance of trusses made of CHS with thick‐walled chords in practice and also to take a first step towards standardization. [ABSTRACT FROM AUTHOR]

The millimeter-wave (mmWave) antennas for smartphones are one of the key components to complete the transition to 5G mobile networks. Although research and development of mmWave 5G antennas for cellular handsets are currently at the center of a significant research effort in both academia and telecommunication industry, a systematic antenna design approved by wireless community has not been proposed yet. With this communication, we propose a novel, high gain, wide band and compact mmWave 5G antenna, namely clover antenna for cellular handsets. The presented antenna has clover like conductor profile whose parameters can be adjusted to obtain high gain or wide band. The designed antennas are simulated with a widely used full-wave analysis tool. Numerical results of the mmWave antenna are confirmed successfully by the experimental results in ${{\text{24}}}$ – ${\text{28}}$  GHz band. The antenna achieves measured peak gain of ${\text{ 7.8}}$ – ${\text{9}}$  dBi in the band. Besides, with a ${\text{16}}$ -element clover antenna array, the beam steering capability of the antenna is demonstrated. Beam steering between ${{ \pm \text{45}^\circ }}$ is achieved with low side lobe levels. Practical design considerations for the integration of the arrays in handset to obtain full-coverage in horizontal plane are investigated. The calculated spatial peak power density values of the proposed array on the outer surface of a head phantom are demonstrated for different scan angles. [ABSTRACT FROM AUTHOR]

This article presents a 60 GHz variable gain amplifier (VGA) with a low phase and output 1‐dB gain compression point (OP1dB) variation for phased‐array applications. The VGA employs a two‐stage modified current‐steering cascode. Implemented in 0.18‐μm SiGe BiCMOS technology, the VGA has a gain control range of 20.4 dB with a maximum gain of 17.7 dB at 60 GHz. The OP1dB variation is only 2.3 dB for all gain states at 60 GHz with a DC power consumption of 50 mW, and the measured phase variation is less than 4.8° at 57 to 66 GHz. [ABSTRACT FROM AUTHOR]

This article presents 64- and 128-element transmit/receive phased-arrays built using SiGe 2 $\times $ 2 quad-chips flipped on a multilayer organic printed-circuit board (PCB). The arrays cover 54–63 GHz with 40–45-dBm effective isotropic radiated power (EIRP) in the TX mode. The antenna elements are stacked microstrip antennas spaced at $0.5\lambda $ in the horizontal plane and $0.7\lambda $ in the vertical plane at 60 GHz, resulting in a scan range of ±50° in azimuth and ±15° in elevation. A 64-QAM 30-Gbps communication link is achieved in the transmit mode when using its full instantaneous bandwidth. This article shows that it is possible to build phased-arrays at 60 GHz and beyond using simple 2 $\times $ 2 quad-chips with low antenna distribution loss, and not using complex chips with 16–32 antenna connections and high distribution loss. Applications include high data-rate point-to-multipoint links, reconfigurable mesh networks, and automotive radars. [ABSTRACT FROM AUTHOR]

In this article, a geometric method, along with the concept of the reference circle, is proposed for the analysis of reflective-type phase shifter (RTPS). Comprehensive analyses of popular reflective loads, including capacitive load (CL), resonated load (RL), and $\pi $ -type load, are presented, revealing their limitations. The triple-resonating load technique is proposed to accomplish a full 360° phase shift range and suppress the loss variation. Further, a systematic design methodology for the RTPS using triple-resonating load is developed. Fabricated in 65-nm CMOS technology, the proposed RTPS occupies a core chip area of $0.076~\mu \text{m}^{2}$. It achieves the first-ever 379° phase shift range at 29 GHz with only one control voltage. With dual-voltage control, a full 360° phase shift range with 8.3 ± 0.2 dB insertion loss is achieved. For both control methods, the return loss is better than 22.8 dB for all phase shift states. [ABSTRACT FROM AUTHOR]

Purpose: To compare the performance of an 8‐channel surface coil/clamshell transmitter and 32‐channel head array coil/birdcage transmitter for hyperpolarized 13C brain metabolic imaging. Methods: To determine the field homogeneity of the radiofrequency transmitters, B1+ mapping was performed on an ethylene glycol head phantom and evaluated by means of the double angle method. Using a 3D echo‐planar imaging sequence, coil sensitivity and noise‐only phantom data were acquired with the 8‐ and 32‐channel receiver arrays, and compared against data from the birdcage in transceiver mode. Multislice frequency‐specific 13C dynamic echo‐planar imaging was performed on a patient with a brain tumor for each hardware configuration following injection of hyperpolarized [1‐13C]pyruvate. Signal‐to‐noise ratio (SNR) was evaluated from pre‐whitened phantom and temporally summed patient data after coil combination based on optimal weights. Results: The birdcage transmitter produced more uniform B1+ compared with the clamshell: 0.07 versus 0.12 (fractional error). Phantom experiments conducted with matched lateral housing separation demonstrated 8‐ versus 32‐channel mean transceiver‐normalized SNR performance: 0.91 versus 0.97 at the head center; 6.67 versus 2.08 on the sides; 0.66 versus 2.73 at the anterior; and 0.67 versus 3.17 on the posterior aspect. While the 8‐channel receiver array showed SNR benefits along lateral aspects, the 32‐channel array exhibited greater coverage and a more uniform coil‐combined profile. Temporally summed, parameter‐normalized patient data showed SNRmean,slice ratios (8‐channel/32‐channel) ranging 0.5‐2.00 from apical to central brain. White matter lactate‐to‐pyruvate ratios were conserved across hardware: 0.45 ± 0.12 (8‐channel) versus 0.43 ± 0.14 (32‐channel). Conclusion: The 8‐ and 32‐channel hardware configurations each have advantages in particular brain anatomy. [ABSTRACT FROM AUTHOR]

Ultraschallwandler werden zum Senden und Empfangen akustischer Wellen eingesetzt und bilden damit das Herzstück eines jeden Ultraschallprüfgeräts. Je nach Anwendung arbeiten sie in unterschiedlichen Frequenzbereichen. Ultraschallwandler mit niedrigen Arbeitsfrequenzen von 1 kHz bis 1 MHz werden insbesondere für Sonaranwendungen benötigt, wohingegen Hochfrequenz-Ultraschallwandler mit Arbeitsfrequenzen von mehr als 15 MHz für die hochauflösende Bildgebung im Rahmen biomedizinischer Untersuchungen und zerstörungsfreier Prüfverfahren interessant sind. Herkömmliche zerstörungsfreie Diagnose- und klinische Ultraschallbildgebungssysteme werden typischerweise mit Ultraschallwandlern, die bei Frequenzen zwischen 1 MHz und 10 MHz arbeiten, betrieben. Im Hinblick auf eine leistungsfähige Auslegung und kosteneffektive Fertigung müssen sowohl die verwendeten piezoelektrischen Komponenten als auch die Größe und innere Struktur solcher Wandler auf den Anwendungsfall zugeschnitten sein. Neben dem Ultraschallwandler, als aktives Element zur Umwandlung von elektrischer Energie in Schallenergie und umgekehrt, werden in einem Ultraschallprüfkopf weitere Komponenten wie Dämpfungskörper und Anpassschichten integriert um die Funktion an die jeweilige Messaufgabe anzupassen. Der Aufbau funktionsfähiger Ultraschallgeräte umfasst darüber hinaus die Ansteuer- und Auswerteelektronik sowie die Bildverarbeitung. Im vorliegenden Artikel werden verschiedene Fertigungstechnologien für Ultraschallwandler unterschiedlicher Frequenzbereiche vorgestellt, die von den Autoren in den vergangenen Jahren entwickelt wurden. 1-3-Piezokomposite auf der Basis von piezokeramischen Fasern können in nahezu jeder Dicke hergestellt werden, was Arbeitsfrequenzen entsprechender Ultraschallwandler zwischen 40 kHz und 8 MHz erlaubt. Das Soft-Mold-Verfahren ermöglicht die Herstellung von Hochfrequenz-Ultraschallwandlern mit Arbeitsfrequenzen von 5 MHz bis 40 MHz. Hochintegrierte Wandler können durch Siebdruck von Elektroden-, Piezokeramik- und Isolationsschichten auf mikroelektronischen Substraten hergestellt werden. Damit sind strukturierte Ultraschallwandler mit Arbeitsfrequenzen zwischen 5 MHz und 30 MHz möglich. Ultrasonic transducers are used for emitting and receiving of acoustic waves and form the core of ultrasonic systems. According to the application field, working frequency of ultrasonic transducers needs to be tailored to a certain value. Low frequency ultrasonic transducers with working frequencies of 1 kHz to 1 MHz are especially interesting for sonar applications, whereas high frequency ultrasonic transducers with working frequencies higher than 15 MHz are favorable for high-resolution imaging in biomedical and non-destructive evaluation. Conventional non-destructive testing devices and clinical ultrasound imaging systems are typically operated with ultrasonic transducers working at frequencies between 1 MHz and 10 MHz. Depending on the operational scenario, piezoelectric material as well as size and inner structure of the ultrasonic transducer has to be customized. Ultrasonic transducers represent the active part of an ultrasonic probe allowing for conversion of electrical energy into sound energy, and vice-versa. Combined with backing and matching layers they form an ultrasonic probe, which than has to be assembled with driving and controlling units to build an ultrasonic system. We here report on our investigation on different manufacturing technologies for ultrasonic transducers in a broad frequency range. 1-3 piezocomposites based on piezoceramic fibers can be fabricated in almost every thickness allowing for transducer frequencies between 40 kHz and 8 MHz. The soft mold process enables the fabrication of high frequency ultrasonic transducers with potential frequencies of 5 MHz up to 40 MHz. Highly integrated ultrasonic transducers can be prepared by screen-printing a sequence of electrode, piezoceramic, and isolation layers on microelectronic substrates. By this, patterned ultrasonic transducers with working frequencies between 5 MHz and 30 MHz are possible. [ABSTRACT FROM AUTHOR]

Purpose: We present a novel, geometrically adjustable, receive coil array whose diameter can be tailored to the subject in order to maximize sensitivity for a range of body sizes. Theory and Methods: A key mechanical feature of the size‐adaptable receive array is its trellis structure that was motivated by similar structures found in gardening and fencing. Our implementation is a cylindrical trellis that features encircling, diagonally interleaved slats, which are linked together at intersecting points. The ensemble allows expansion or contraction to be controlled with the angle between the slats. This mechanical frame provides a base for radiofrequency coils wherein approximately constant overlap, and therefore coupling between adjacent elements, is maintained when the trellis is expanded or contracted. We demonstrate 2 trellis coil concepts for imaging lower extremity at 3T: a single‐row 8‐channel array built on a trellis support structure and a multirow 24‐channel array in which the coil elements themselves form the trellis structure. Results: We show that the adjustable trellis array can accommodate a range of subject sizes with robust signal‐to‐noise ratio, loading, and coupling. Conclusion: The trellis coil concept enables an array of surface coils to expand and contract with negligible effect on tuning, matching, and decoupling. This allows an encircling array to conform closely to anatomy of various sizes, which provides significant gains in signal‐to‐noise ratio. [ABSTRACT FROM AUTHOR]

Abstract A 28 GHz fully integrated 4-channel TX/RX 5G beam-forming transceiver is implemented in 65-nm CMOS technology. Each TX/RX channel can be digitally controlled with 5.625 ° phase step and 2 dB gain step. The transceiver employs a heterodyne architecture with 6 GHz intermediate frequency (IF). The transceiver works in a band of frequencies between 26 GHz and 30 GHz. The up/down-conversion mixers are integrated on the same chip with a shared LO chain. The phased-array power combining/splitting is done using a Wilkinson power combiner/divider. Each channel features 3.4–3.9 dB NF and −5 to −3.5 dBm IIP3 in RX mode, high OP1dB of 14.7 dBm and 18 dB gain in TX mode. The maximum rms amplitude and phase error for each channel is 0.25 dB and 1.5 ° across gain and phase states, respectively. The RFIC area is 5.29 × 3.4 mm2 including pads and it consumes 240 mW per channel in TX mode, 120 mW per channel in RX mode and 174 mW for the LO chain with a total power of 1.58 W from a 1.2 V supply. [ABSTRACT FROM AUTHOR]

The development of reliable structural health monitoring techniques is enabling a healthy transition from preventive to condition-based maintenance, hence leading to safer and more efficient operation of different industries. Ultrasonic guided-wave based beamforming is one of the most promising techniques, which supports the monitoring of large thin-walled structures. However, beamforming has been typically applied to the post-processing stage (also known as virtual or receiver beamforming) because transmission or physical beamforming requires complex hardware configurations. This paper introduces an electronic structural health monitoring system that carries out transmission beamforming experiments by simultaneously emitting and receiving ultrasonic guided-waves using several transducers. An empirical characterization of the transmission beamforming technique for monitoring an aluminum plate is provided in this work. The high signal-to-noise ratio and accurate angular precision of the physical signal obtained in the experiments suggest that transmission beamforming can increase the reliability and robustnessof this monitoring technique for large structures and in real-world noisy environments.